There exist a variety of portable combustion devices that may be used, for example, as a stove for cooking or heating, among other uses. In the past, portable combustion devices required a variety of fuels such as those used for liquid fuel stoves, portable and fixed wood stoves and compressed gas fuel stoves. These stoves were used in a variety of different situations such as for camping, emergency or rescue situations, during a power outage or a similar scenario when traditional larger-scale cooking sources (for example gas/electric cooking rages and barbeque grilles) are not available.
While previous devices did provide a combustion device, they all had the similar drawback that they all required a special fuel source. Whether the fuel was kerosene, gasoline, propane or a similar fuel source they all required some canister of fuel to be purchased and carried along with the combustion device. These canisters may be a single use canisters or multi-use canister. However, once the fuel is expended, an additional fuel canister must be supplied to maintain combustion. The availability of fuel poses a serious drawback should the canister run out, especially if used for hiking, or emergency situations. Likely, it is impossible to obtain a new canister of gas or liquid fuel while out camping or during an emergency, and even if it is possible, there is no guarantee that the person would be able to find replacements for their type of fuel and canister. Therefore the operator is required to bring extra canisters of fuel, which adds more weight, and the canisters become yet another accessory that must be carried in additional to device. Moreover, should a person need to use their portable combustion device for an extended length of time, carrying a multitude of canisters for fuel becomes impractical.
Additionally, the canisters of fuel must be disposed of properly after use. Since the canisters are often under pressure and most fuels are harmful or toxic, the canisters can not be left behind at a campsite, or during an emergency scenario. In some cases the canister may not be thrown away like other types of trash, but need to be disposed in a special manner. With a variety of fuels, canister types, and portable combustion devices, which are all made by different companies a person would limited in their options and be forced to continue to use a single fuel source.
Aside from the traditional campfire, there have been several attempts to overcome the disadvantages associated with fuel-burning cooking/heating appliances, one such attempt being a biomass combustion device or biomass stove. A biomass stove is able to burn a variety of biomass fuels such that a person would not be required to supply a compressed liquid fuel source for their portable combustion device. The user could employ whatever fuel is available to achieve the same combustion results as the previous devices. Additionally, the user need not dispose of potentially toxic canisters, and he or she would not be required to carry the appliance's fuel source with him or her. Also, whatever fuel unused, can simply be left behind.
In fact, in many developing countries some form of biomass combustion or biomass stove, burning wood chips, twigs, leaves, peat, etc. (or low-grade coal in some instances) is often used as the primary cooking device for the family meal. Generally the biomass combustion is carried out in some form of simple fire-driven stove, which is used for both heating and cooking. However, biomass devices typically have drawbacks that render them undesirable in many situations. For example, biomass stoves are not “clean” burning, that is they produce soot and smoke during the combustion process, which can cover pots, pans, or even food during the combustion. Also, the smoke generated during the combustion process can make the biomass stoves potentially dangerous for indoor use—as the smoke contains large quantities of soot and other toxic combustion products, including carbon monoxide. Nevertheless, such stoves are often used in small indoor spaces with inadequate ventilation in developing countries. In addition, many biomass stoves are heavy, making them less suitable for field use, as they are not easily portable.
One technique for increasing the efficiency of combustion is to provide a driven airflow through the biomass using powered fan, using a variety of motive power sources including, but not limited to, spring and clockwork mechanisms, compressed air/gas and electricity. In the field, the fan is typically driven by a battery or other electrical source. However, batteries may have a short life in use, and/or be discharged (dead), or be in need of recharging, when needed. In addition, batteries are expensive and often unavailable to peoples of developing countries. In addition, batteries are environmentally unfriendly and often disposed of improperly.
Accordingly, it is desirable to provide a portable combustion device that is capable of being used as a stove for cooking and/or heating, which burns commonly available wood and other biomass, and provides similar heat output as other liquid or gas fuels, without the need for batteries or disposable/refillable canisters of fuel. The stove can desirably be easy to carry, low-maintenance and burn fuel without exhausting significant soot, smoke or toxic combustion byproducts. The stove can desirably employ inexpensive and commercially available components and conventional construction techniques in its manufacture.
U.S. Pat. No. 8,297,271, issued Oct. 31, 2012, entitled PORTABLE COMBUSTION DEVICE UTILIZING THERMOELECTRICAL GENERATION, by Jonathan M. Cedar and Alexander H. Drummond, describes a portable combustion stove, the teachings of which are herein incorporated by reference.